Synoptic analysis and simulation of an unusual dust event over the Atacama Desert

Mark Reyers,Yaping Shao,Mehdi Hamidi

doi:10.1002/asl.899

Mark Reyers, Yaping Shao + Show 1 more

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AbstractAn unusual dust event over the Atacama Desert occurred in July 2016. Here, a synoptic study of the event is carried out using the NCEP FNL analysis data and WRF‐chem simulations. The “zonalization” of a mid‐tropospheric trough leads to the formation of a horizontal convergence band over the Northern Atacama and thus downward wind below it. As the descending air masses warm adiabatically, strong temperature contrasts to the colder air over the western Andes occur and intensify the down‐valley winds, thus leading to extraordinary strong easterly winds in the Atacama. Simulations with WRF‐chem indicate that these surface winds are sufficient for large‐scale dust emission, and simulated dust plumes traveling far over the eastern South Pacific agree well with the observations. As the integrated dust load is comparable with the load observed in major dust sources of the world, our findings highlight the importance of such unusual events.

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The results of the Weather Research and Forecasting Model (WRF)-chem simulation show a good consistency with the observations in terms of wind characteristics and the propagation of the dust plumes
On a public research platform for example it is hypothesized that a convergence zone of an upper level jet streak located over the Atacama Desert facilitated the formation of a high pressure ridge, which pushed strong winds off-shore
We found that convergence zone associated with the entrance region of the jet streak was located over the Pacific and not over the Atacama Desert

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A synoptic study of the event is carried out using the NCEP FNL analysis data and WRF-chem simulations. Simulations with WRF-chem indicate that these surface winds are sufficient for large-scale dust emission, and simulated dust plumes traveling far over the eastern South Pacific agree well with the observations. KEYWORDS analysis, Atacama Desert, dust event, dynamic/processes, simulation, wind 1 | INTRODUCTION

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